Fossilized Shark Tooth
Chondrichthyes (Class)
fossil
Category
Mineral Composite
Browse mineral composite specimens identified by the Rock Identifier community.
Learn about Mineral Composite in the encyclopedia
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Vesicular basalt (likely weathered lava rock)
Vesicular basalt; primarily plagioclase feldspar, pyroxene, and volcanic glass, with possible iron-oxide alteration
igneous
Weathered basalt pebble
Basalt, a fine-grained mafic volcanic rock; likely olivine- and pyroxene-bearing
igneous
Amethyst (likely tumbled or polished)
Quartz, SiO₂; purple color commonly caused by trace iron and natural irradiation
mineral
Tumbled amethyst
Quartz, SiO₂; purple color typically from trace iron and natural irradiation
gemstone
Yellow Quartz
Silicon Dioxide (SiO2)
mineral
Sandstone
Sandstone (Quartzose/Feldspathic Sandstone)
sedimentary
Marble
Metamorphic Limestone (CaCO3)
metamorphic
Marble
Recrystallized Calcite (CaCO3)
metamorphic
Marble
Metamorphosed Limestone (principally CaCO3)
metamorphic
Sandstone
Sedimentary Rock (Quartzose Sandstone)
sedimentary
Banded Gneiss Pebble
Gneiss (Metamorphic Rock)
metamorphic
Sandstone
Sedimentary Rock (Quartz Arenite)
sedimentary
Likely gneiss pebble
Gneiss, a foliated metamorphic rock composed mainly of quartz, feldspar, and mica
metamorphic
Weathered vesicular volcanic rock (likely basalt or andesite)
Amygdaloidal basalt/andesite; cavities may contain calcite, zeolites, or silica minerals
igneous
Tumbled or weathered gneiss
Feldspar–quartz–mica gneiss (composition variable)
metamorphic
Amygdaloidal Basalt
Amygdaloidal Basalt (Mafic Extrusive volcanic rock)
igneous
Rainbow Fluorite
Fluorite (Calcium Fluoride, CaF2)
mineral
Sandstone (Pebble)
Arenite (primarily SiO2)
sedimentary
Sandstone (Quartzose Sandstone)
Arenite
sedimentary
Pegmatitic granite (likely quartz–feldspar rock)
Granitic pegmatite, composed mainly of quartz (SiO₂) and feldspar
igneous
Milky quartz fragment
Quartz, silicon dioxide (SiO₂)
mineral
Blue Apatite
Apatite (Ca5(PO4)3(F,Cl,OH))
mineral
Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
mineral
Fluorite
Calcium fluoride (CaF2)
mineral
Malachite and Azurite on Gossan (Ironstone Matrix)
Cu2CO3(OH)2 (Malachite) on FeO(OH)·nH2O (Limonite/Gossan)
mineral
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Metamorphosed mafic rock, likely amphibolite
Amphibolite, chiefly hornblende + plagioclase; possibly mafic gneiss or altered basalt
metamorphic
Granite
Intrusive Igneous Rock (composed of quartz, alkali feldspar, and plagioclase)
igneous
Note regarding baguette production (not a rock)
Digital text image - Somali language
not a rock
Small unidentified mineral specimen
Indeterminate from image; possibly a quartz-family crystal or sulfide mineral
mineral
Quartz-rich pegmatite (likely mica-bearing granite)
Granitic pegmatite; chiefly quartz (SiO₂), feldspar, and mica (muscovite/biotite)
igneous
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Snowflake Obsidian
Obsidian with Cristobalite inclusions
igneous
Calcite
Calcite (Mineral; CaCO₃)
Mineral
Granite Pebble
Granite
igneous
Chrysocolla-bearing rock (likely chrysocolla in a host rock)
Chrysocolla, hydrated copper aluminosilicate: approximately (Cu,Al)₂H₂Si₂O₅(OH)₄·nH₂O
mineral
Agate / Chalcedony Geode
Silicon Dioxide (SiO2)
sedimentary
Blue Apatite
Calcium phosphate mineral, Ca5(PO4)3(F,Cl,OH)
mineral
Schist
Schist; commonly mica schist, composed chiefly of muscovite/biotite mica with quartz and feldspar
metamorphic
Quartz (Druzy or Chalcedony variant)
Silicon Dioxide (SiO2)
mineral